Halo-Ed: Extreme Microbiology and Astrobiology
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Introduction	Mutations Using the model microbe Halobacterium sp. NRC-1, students may study the process of mutation which occurs at high frequency by performing DNA extractions, PCR (polymerase chain reaction), and gel electrophoresis. This activity, called the Genotype-Phenotype Connection, is designed in inquiry format and involves both the wild-type Halobacterium sp. NRC-1 and a stable mutant derivative, Halobacterium sp. KBT-1, which was identified by a Kansas Biology teacher. As part of these exercises, students formulate questions and hypotheses to explain differences in colony phenotypes. To draw conclusions regarding the link between the molecular (genotype) differences detected and the phenotypes observed, students pool and analyze their data. For more information, see: Genotype-Phenotype Connection See images of Halobacterium sp. NRC-1 plates: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 and mutant colonies: Mut1, Mut2 Some interesting questions for students to consider: Why are some colonies pink and some red? What is a mutation? What are gas vesicle nanoparticles? How do transposable elements cause mutations such as those shown below? For more on the microbial colonies and their appearance, see the following research articles. Note that Professor Shiladitya DasSarma discovered and characterized the first Haloarchaeal transposable element (ISH1 or Insertion Sequence in Haloarchaea Ref #2 below) in 1982: 1. Read, H.A., DasSarma, and S.R. Jaskunas. 1980. Fate of Donor Insertion Sequence IS1 during Transposition. Proc. Natl. Acad. Sci. USA 77:2514-2518. 2. Simsek, M., DasSarma, U.L. RajBhandary, and H.G. Khorana. 1982. A transposable element from Halobacterium halobium which inactivates the bacteriorhodopsin gene. Proc. Natl. Acad. Sci. USA 79:7268-7272. See excerpted figures below. 3. Jones, J.G., N.R. Hackett, J.T. Halladay, D.J. Scothorn, C.-F. Yang, W.-L. Ng, and DasSarma, S. 1989. Analysis of insertion mutants reveals two new genes in the pNRC100 gas vesicle gene cluster of Halobacterium halobium. Nucleic Acids Res. 17:7785-7793. 4. Ng, W.-L., S. Kothakota, and DasSarma, S. 1991. Structure of the Gas Vesicle Plasmid in Halobacterium halobium: Inversion Isomers, Inverted Repeats, and Insertion Sequences. J. Bacteriol. 173:1958-1964. 5. Charlebois, R.L, and DasSarma. 1995. Insertion Elements of Halophiles in "Archaea: A Laboratory Manual - Halophiles", Cold Spring Harbor Laboratory Press, Cold Spring Harbor, NY, pp. 253-255. For more on the corn - see Wiki article on Late Nobel Laureate Dr. Barbara McClintock, who won the Nobel Prize for Physiology or Medicine in 1983 (the first woman to win this prize unshared). As a companion to this website, we have developed a comprehensive set of laboratory exercises using Halobacterium NRC-1 as the model organism for teaching a wide range of subjects, including exponential growth, colony formation, mutation, antibiotic resistance, motility, flotation, DNA function, transformation, complementation, biotechnology, genomics, and bioinformatics. For Questions and Suggestions, contact the Halo-Ed Team
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